Preparation method of triethylamine gas sensor of metal (Au, Fe, Co, Ni, Ru and like, taking Au as example) loaded zinc oxide composite material

Abstract

The invention relates to a preparation method of a metal (Au, Ni, Co, Fe, Ru and the like, wherein Au is taken as an example in the invention) loaded ZnOx material triethylamine gas sensor. The preparation method is simple and easy to operate, firstly, ZIF-8 is prepared under the condition of normal temperature, secondly, a substrate material ZnOx is prepared through a calcination method, and then Au atoms are loaded on the substrate through an impregnation method. Wherein ZnOx is granular, and the size of the ZnOx is 20-50nm; au is in a monatomic state and is uniformly distributed in ZnOx, and the loading capacity is 0.5-7.5 wt%. The triethylamine gas sensor has excellent performance in the aspect of triethylamine gas detection, the problems that an existing device is high in working temperature, low in sensitivity, long in response / recovery time, poor in selectivity and the like are solved, and rapid and accurate detection of triethylamine at the low working temperature is achieved.

Description

Technical Field

[0001] The present invention relates to a preparation method for a triethylamine gas sensor, and particularly to a preparation method for a gas sensor of a metal-loaded zinc oxide composite material for triethylamine gas recognition. Technical Background

[0002] Triethylamine, as a common organic compound, is widely used in industrial production such as pharmaceuticals, rubber, and dyes. Triethylamine has an irritating odor, and long-term contact or exposure to triethylamine may pose potential hazards to human health and the environment. In an environment that may be contaminated by triethylamine, it is very necessary to quickly and accurately detect triethylamine gas. In addition, triethylamine is one of the main components of the fishy smell of seafood, and its content is regarded as an important indicator of food freshness.

[0003] Traditional metal oxide semiconductor sensors have been widely used in the field of gas detection due to their excellent sensitivity, stability, and response speed. However, traditional metal oxide semiconductor triethylamine sensors still have some deficiencies, such as high operating temperature, poor gas selectivity, and poor long-term stability, etc. These problems limit their performance in practical applications.

[0004] Therefore, the present invention provides a preparation method for a gas sensor of a metal-loaded zinc oxide composite material for triethylamine gas recognition, which improves the performance of traditional metal oxide semiconductor sensors and enhances the sensitivity and long-term stability for detecting triethylamine target gas. Summary of the Invention

[0005] The present invention provides a preparation method for a triethylamine gas sensor, and particularly to a preparation method for a gas sensor of a metal-loaded zinc oxide composite material for triethylamine gas recognition.

[0006] (1) Add 0.8 - 1.0 g of Zn(NO 3 ) 2 ·6H 2 O to 25 mL of methanol solution, and stir for 20 min to obtain solution A;

[0007] (2) Dissolve 0.9 - 1.1 g of 2-methylimidazole in 25 mL of methanol solution, and stir for 20 min to obtain solution B;

[0008] (3) Mix solution A and solution B, stir for 5 - 6 min, and stand for 72 h to obtain a precipitate;

[0009] (4) Wash the precipitate obtained in step (3) several times with deionized water and absolute ethanol, and dry at 60 - 80 °C for 24 - 48 h to obtain a powder material;

[0010] (5) Anneal the material obtained in step (4) in a muffle furnace at 300 - 500 °C for 2 - 5 h, and then cool it to room temperature to obtain ZnO x material;

[0011] (6) Take a certain amount of ZnO x material, add 1 - 2 mL of ethanol, add a series of different amounts of chloroauric acid solution, stir and react for 3 - 8 h, dry it in an oven at 65 - 75 °C, and wash it to obtain sensing materials with different Au loadings.

[0012] (7) Take 4.5 - 5.5 mg of the composite material obtained in step (6), add 95 - 100 μL of absolute ethanol, and then ultrasonicate for 8 - 15 min, and coat it on the surface of the ceramic tube; among them, the coating thickness is 10 - 20 μm.

[0013] (8) After drying the ceramic tube coated with the gas-sensitive material, place it in a muffle furnace, heat it up to 300 °C and anneal it for 10 - 12 h, and then naturally cool it to room temperature; pass a nickel-chromium alloy heating coil with a resistance value of 30 - 40 Ω through the inside of the ceramic tube as a heating wire, and weld it to the ceramic tube on the base together to make a gas sensor device.

[0014] Among them, the annealing temperature in step (5) is 300 - 500 °C.

[0015] The ZnO x material in step (6) is 30 - 50 mg. The volume of the chloroauric acid solution is 1 - 100 μL, and the concentration is 100 mg / mL.

[0016] The present invention has the following advantages compared with the prior art:

[0017] (1) The present invention first prepares ZIF-8 material, and then uniformly loads a trace amount of precious metal Au on the surface of the material by an impregnation method; the manufacturing process is simple and the cycle is short.

[0018] (2) The Au-loaded ZnO x composite material prepared by the present invention, by virtue of its large specific surface area and precious metal loading, greatly improves the sensitive characteristics of the gas sensor, has excellent sensitivity and selectivity to triethylamine, and at the optimal working temperature of 250 °C, the sensitivity to 20 ppm triethylamine is 110 - 130. The detection limit of the gas sensor using this composite material for triethylamine is 1 ppm.

[0019] (3) The preparation of the present invention is simple, suitable for mass production, the prepared triethylamine gas sensor has a wide working range, and has important application value. Description of the Drawings

[0020] Figure 1Shown is the XRD pattern of the material obtained in Step Implementation (4) and Example 2;

[0021] Figure 2 Shown is the Au-loaded ZnO x composite material obtained in Example 2;

[0022] Figure 3 Shown is the Au-loaded ZnO x composite material obtained in Example 2;

[0023] Figure 4 Shown is the Au-loaded ZnO x composite material and the ZnO x composite material obtained in Comparative Example 1; XPS pattern of O;

[0024] Figure 5 Shown is the Au-loaded ZnO x composite material and the ZnO x composite material obtained in Comparative Example 1; XPS pattern of Zn;

[0025] Figure 6 Shown is the Au-loaded ZnO x composite material; XPS pattern of Au;

[0026] Figure 7 Shown is the sensitivity graph of the materials obtained in Comparative Example 1 and Examples 1 to 4 to 20 ppm triethylamine at different temperatures;

[0027] Figure 8 Shown is the Au-loaded ZnO x composite material obtained in Example 2; sensitivity graph to 20 ppm different gases at 250 °C;

[0028] Figure 9 Shown is the Au-loaded ZnO x composite material obtained in Example 2; response curve graph to 20 ppm triethylamine at 250 °C;

[0029] Figure 10 Shown is the Au-loaded ZnO x composite material obtained in Example 2; continuous response curve to triethylamine gas at 250 °C;

[0030] Figure 11 Shown is the Au-loaded ZnO x composite material obtained in Example 2; continuous response-recovery curve to 20 ppm triethylamine gas at 250 °C;

[0031] Figure 12Shown as the Au-loaded ZnO obtained in Example 2 x Long-term response and recovery curves of the composite material to 20 ppm triethylamine gas at 250 °C; Detailed implementation method

[0032] On the surface of the Al 2 O 3 ceramic tube, prepare a Au-loaded ZnO x thin film. The Al 2 O 3 ceramic tube is internally provided with a heating coil for heating the Al 2 O 3 ceramic tube. Lead out the electrodes of the heating wire and the platinum wire on the Au-loaded Al 2 O 3 film and connect them to the lead-out circuit and the test circuit respectively. Use its resistance change with the concentration of the test gas in the environment to determine the presence of the test gas. The gas sensor shows gas-sensing characteristics of high selectivity, high sensitivity and short response / recovery time to triethylamine.

[0033] Sensitivity test method: Regulate the working temperature of the sensor by changing the current of the heating coil. The sensitivity of the sensor can be obtained by measuring the resistance value (Ra) of the sensor in air and the resistance value (Rg) in the gas to be measured. The sensitivity of the sensor to triethylamine is defined as S = Ra / Rg. Through the characteristic curve of sensitivity to gas concentration, the detection of the unknown concentration of triethylamine gas can be realized. The test environment is: temperature: 25 ± 5 °C, relative humidity: 40 ± 5% RH.

[0034] Comparative Example 1:

[0035] (1) Add 0.8 - 1.0 g of Zn(NO 3 ) 2 ·6H 2 O to 25 mL of methanol solution and stir for 20 min to obtain solution A;

[0036] (2) Dissolve 0.9 - 1.1 g of 2-methylimidazole in 25 mL of methanol solution and stir for 20 min to obtain solution B;

[0037] (3) Mix solution A and solution B, stir for 5 - 6 min, and let it stand for 72 h to obtain a precipitate;

[0038] (4) Wash the precipitate obtained in step (3) several times with deionized water and absolute ethanol, and dry it at 60 - 80 °C for 24 - 48 h to obtain a powder material;

[0039] (5) Anneal the material obtained in step (4) in a muffle furnace at 300 - 500 °C for 2 - 5 h, and then cool it to room temperature to obtain ZnOx Material;

[0040] (6) Take 4.5 - 5.5 mg of the composite material obtained in step (5), add 95 - 100 μL of absolute ethanol, and then ultrasonicate for 8 - 15 min, and coat it on the surface of the ceramic tube; wherein, the coating thickness is 10 - 20 μm;

[0041] (8) After drying the ceramic tube coated with the gas-sensitive material, place it in a muffle furnace, heat it to 300 °C and anneal for 10 - 12 h, and then naturally cool to room temperature; Pass a nickel-chromium alloy heating coil with a resistance value of 30 - 40 Ω through the inside of the ceramic tube as a heating wire, and weld it together with the ceramic tube on the base to make a gas sensor device.

[0042] Example 1:

[0043] (1) Add 0.8 - 1.0 g of Zn(NO 3 ) 2 ·6H 2 O to 25 mL of methanol solution, and stir for 20 min to obtain solution A;

[0044] (2) Dissolve 0.9 - 1.1 g of 2-methylimidazole in 25 mL of methanol solution, and stir for 20 min to obtain solution B;

[0045] (3) Mix solution A and solution B, stir for 5 - 6 min, and let it stand for three days to obtain a precipitate;

[0046] (4) Wash the precipitate obtained in step (3) several times with deionized water and absolute ethanol, and dry it at 60 - 80 °C for 24 - 48 h to obtain a powder material;

[0047] (5) Anneal the material obtained in step (4) in a muffle furnace at 300 - 500 °C for 2 - 5 h, and then cool it to room temperature to obtain ZnO x Material;

[0048] (6) Take a certain amount of ZnO x Material, add 1 - 2 mL of ethanol, add 5 μL of chloroauric acid solution, stir and react for 3 - 8 h, and dry it in an oven at 65 - 75 °C, and wash it to obtain a sensing material with different Au loadings;

[0049] (7) Take 4.5 - 5.5 mg of the composite material obtained in step (6), add 95 - 100 μL of absolute ethanol, and then ultrasonicate for 8 - 15 min, and coat it on the surface of the ceramic tube; wherein, the coating thickness is 10 - 20 μm;

[0050] (8) After drying the ceramic tube coated with the gas-sensitive material, it is placed in a muffle furnace, heated to 300 °C and annealed for 10 - 12 h, and then naturally cooled to room temperature; a nickel-chromium alloy heating coil with a resistance value of 30 - 40 Ω is passed through the inside of the ceramic tube as a heating wire, and is welded to the base together with the ceramic tube to make a gas sensor device.

[0051] Example 2:

[0052] (1) Add 0.8 - 1.0 g of Zn(NO 3 ) 2 ·6H 2 O to 25 mL of methanol solution, stir for 20 min to obtain solution A;

[0053] (2) Dissolve 0.9 - 1.1 g of 2-methylimidazole in 25 mL of methanol solution, stir for 20 min to obtain solution B;

[0054] (3) Mix solution A and solution B, stir for 5 - 6 min, and let stand for 72 h to obtain a precipitate;

[0055] (4) Wash the precipitate obtained in step (3) several times with deionized water and absolute ethanol, and dry it at 60 - 80 °C for 24 - 48 h to obtain a powder material;

[0056] (5) Anneal the material obtained in step (4) in a muffle furnace at 300 - 500 °C for 2 - 5 h, and then cool to room temperature to obtain ZnO x material;

[0057] (6) Take a certain amount of ZnO x material, add 1 - 2 mL of ethanol, add 10 μL of chloroauric acid solution, stir and react for 3 - 8 h, and dry it in an oven at 65 - 75 °C, and wash it to obtain a sensing material with different Au loadings;

[0058] (7) Take 4.5 - 5.5 mg of the composite material obtained in step (6), add 95 - 100 μL of absolute ethanol, and then ultrasonically treat for 8 - 15 min, and coat it on the surface of the ceramic tube; among them, the coating thickness is 10 - 20 μm;

[0059] (8) After drying the ceramic tube coated with the gas-sensitive material, it is placed in a muffle furnace, heated to 300 °C and annealed for 10 - 12 h, and then naturally cooled to room temperature; a nickel-chromium alloy heating coil with a resistance value of 30 - 40 Ω is passed through the inside of the ceramic tube as a heating wire, and is welded to the base together with the ceramic tube to make a gas sensor device.

[0060] Example 3:

[0061] (1) Add 0.8 - 1.0 g of Zn(NO 3 )2 ·6H 2 O was added to 25 mL of methanol solution and stirred for 20 min to obtain solution A;

[0062] (2) 0.9 - 1.1 g of 2 - methylimidazole was dissolved in 25 mL of methanol solution and stirred for 20 min to obtain solution B;

[0063] (3) Solution A and solution B were mixed, stirred for 5 - 6 min, and left standing for 72 h to obtain a precipitate;

[0064] (4) The precipitate obtained in step (3) was washed several times with deionized water and absolute ethanol, and dried at 60 - 80 °C for 24 - 48 h to obtain a powder material;

[0065] (5) The material obtained in step (4) was annealed in a muffle furnace at 300 - 500 °C for 2 - 5 h, and then cooled to room temperature to obtain ZnO x material;

[0066] (6) A certain amount of ZnO x material was added to 1 - 2 mL of ethanol, 20 μL of chloroauric acid solution was added, and the mixture was stirred and reacted for 3 - 8 h, and then dried in an oven at 65 - 75 °C and washed to obtain a sensing material with different Au loadings;

[0067] (7) 4.5 - 5.5 mg of the composite material obtained in step (6) was taken, 95 - 100 μL of absolute ethanol was added, and then ultrasonicated for 8 - 15 min and coated on the surface of the ceramic tube; among them, the coating thickness was 10 - 20 μm;

[0068] (8) The ceramic tube coated with the gas - sensitive material was dried and then placed in a muffle furnace, heated to 300 °C and annealed for 10 - 12 h, and then naturally cooled to room temperature; a nickel - chromium alloy heating coil with a resistance value of 30 - 40 Ω was passed through the inside of the ceramic tube as a heating wire, and was welded to the base together with the ceramic tube to make a gas sensor device.

[0069] Example 4:

[0070] (1) 0.8 - 1.0 g of Zn(NO 3 ) 2 ·6H 2 O was added to 25 mL of methanol solution and stirred for 20 min to obtain solution A;

[0071] (2) 0.9 - 1.1 g of 2 - methylimidazole was dissolved in 25 mL of methanol solution and stirred for 20 min to obtain solution B;

[0072] (3) Solution A and solution B were mixed, stirred for 5 - 6 min, and left standing for 72 h to obtain a precipitate;

[0073] (4) Wash the precipitate obtained in step (3) several times with deionized water and absolute ethanol, and dry it at 60 - 80 °C for 24 - 48 h to obtain a powder material;

[0074] (5) Anneal the material obtained in step (4) in a muffle furnace at 300 - 500 °C for 2 - 5 h, and then cool it to room temperature to obtain ZnO x material;

[0075] (6) Take a certain amount of ZnO x material, add 1 - 2 mL of ethanol, add 40 μL of chloroauric acid solution, stir and react for 3 - 8 h, dry it in an oven at 65 - 75 °C, and wash it to obtain sensing materials with different Au loadings;

[0076] (7) Take 4.5 - 5.5 mg of the composite material obtained in step (6), add 95 - 100 μL of absolute ethanol, and then ultrasonicate for 8 - 15 min, and coat it on the surface of the ceramic tube; among them, the coating thickness is 10 - 20 μm;

[0077] (8) After drying the ceramic tube coated with the gas - sensitive material, place it in a muffle furnace, heat it up to 300 °C and anneal it for 10 - 12 h, and then naturally cool it to room temperature; Pass a nickel - chromium alloy heating coil with a resistance value of 30 - 40 Ω through the inside of the ceramic tube as a heating wire, and weld it together with the ceramic tube on the base to make a gas sensor device.

Claims

1. A method for preparing a triethylamine gas sensor of a metal (Au, Fe, Co, Ni, Ru, etc., Au is used as an example in this paper) loaded zinc oxide composite material, comprising establishing a triethylamine gas sensor based on a zinc oxide composite material. The specific steps are as follows: (1) Preparation of ZIF-8 at room temperature; (2) The precursor ZIF-8 prepared in step (1) was calcined in a muffle furnace at 300-500°C for 3h. After cooling to room temperature, the base material ZnO was obtained. x ; (3) Take ZnO x Materials, a series of different amounts of chloroauric acid solution were added to obtain triethylamine gas sensing materials with different Au loading amounts, named ZIF-8 / Au; (4) ZIF-8 / Au was added to ethanol for ultrasonic treatment, and then the material was coated on the surface of an Al2O3 ceramic tube, aged at high temperature for 12 h, a heating wire was added, and the triethylamine sensor was made after being welded to the base.

2. The preparation method according to claim 1, characterized in that: The process of preparing ZIF-8 at room temperature in step (1) is: (5) Add 0.8-1.0 g of Zn(NO3)2·6H2O to 25 mL of methanol solution and stir for 20 min to obtain solution A; (6) Dissolve 0.9-1.1 g of 2-methylimidazole in 25 mL of methanol solution and stir for 20 min to obtain solution B; (7) Mix solution A and solution B, stir for 5 to 6 minutes, and let stand for 72 hours to obtain a precipitate; (8) The precipitate obtained in step (3) is washed several times with deionized water and anhydrous ethanol, and dried at 60-80° C. for 24-48 h to obtain a powder material, namely ZIF-8.

3. The preparation method according to claim 1-2, characterized in that: The process of preparing the ZIF-8 / Au gas sensor in step (3) is as follows: (9) The material obtained in step (8) is calcined in a muffle furnace at 300-500° C. for 2-5 h, and then cooled to room temperature to obtain ZnO x Material; (10) Take a certain amount of ZnO x Add 1-2 mL of ethanol to the material, add a series of different amounts of chloroauric acid solution, stir and react for 3-8 h, dry in an oven at 65-75 ° C, and wash to obtain sensing materials with different Au loading amounts; (11) taking 4.5-5.5 mg of the composite material obtained in step (10), adding 95-100 uL of anhydrous ethanol, ultrasonicating for 8-15 min, and coating it on the surface of the ceramic tube; wherein the coating thickness is 10-20 μm; (12) The ceramic tube coated with the gas-sensitive material is dried and placed in a muffle furnace, heated to 300° C. and calcined for 10 to 12 hours, and naturally cooled to room temperature; a nickel-chromium alloy heating coil with a resistance value of 30 to 40 Ω is passed through the interior of the ceramic tube as a heating wire, and is welded together with the ceramic tube to a fixed base to make a triethylamine gas sensor.

4. Au-loaded ZnO as described in claims 1-3 x The preparation method of the composite material triethylamine gas sensor is characterized by: The calcination temperature of step (9) is 300-500° C.; the aging environment is air aging; and the heating rate is 3° C. / min.

5. Au-loaded ZnO as described in claims 1-3 x The preparation method of the composite material triethylamine gas sensor is characterized by: The ZnO in step (11) x The material is 30-50 mg. The volume of chloroauric acid solution is 1-100 uL, and the concentration is 100 mg / mL.

6. A ZnO-based x The triethylamine gas sensor is used for a method of detecting triethylamine, characterized in that: The metal oxide ZnO used in step (11) x It is a granular material with a size of 20-50nm; Au is evenly distributed in ZnOx in a single atomic state, with a loading of 0.5-7.5wt%. It has more active sites and a larger specific surface area, and has a good adsorption effect with triethylamine.

7. The triethylamine gas sensor prepared by the preparation method according to any one of claims 1 to 6, wherein the triethylamine sensor is a resistive triethylamine sensor.

8. Use of the triethylamine sensor according to claims 1-7 in detecting triethylamine under high temperature conditions.

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